Sheila Swanson's second career as an in-your-face political agitator began after she learned she had cancer in her left breast. Again.

It was a "second primary," a brand-new tumor unrelated to the one she had survived in 1979. The first time she had the lump out and got on with her life. This time she got angry.

Swanson had both breasts cut off, quit working as a nurse and vowed to do everything she could to make sure that her daughter and other women's children would not have to go through this too.

"I looked at my life and said I have to make some sense out of getting this disease a second time. I decided I had to become outspoken and not be one of the silent women," said Swanson of Saratoga, Calif.

So with a friend, she founded the Bay Area Cancer Network in 1990 and set to work waking up the world. About the same time all over the country, lots of other people--and not all of them women--got the same idea.

Dozens of groups have sprung up: people with prostate cancer, people with kidney cancer, relatives of people with Alzheimer's disease. All over the country, these victims of disease have stopped waiting quietly for medical science to proceed at its usual regal pace.

They want cures. They want prevention. They want big, big federal research budgets for what's killing them. And they want them now.

Members of this new category of political agitator freely acknowledge that they have a stunningly successful teacher--the AIDS movement. Using everything from old-fashioned lobbying to street theater, AIDS activists made their disease the most richly funded target, tied with cancer, on the federal research agenda.

With similar tactics, these latest crusaders are already shifting the way money is divided up among disease researchers.

"The advocacy groups have demonstrated the influence that articulate, well-organized, very vocal, very angry people can have on resource allocation," said Dr. Robert Wachter of UC San Francisco.

Last fall, the activists and their champions in Congress succeeded in getting the budget of the National Cancer Institute--the government's primary supporter of cancer research--increased by 14%. Moreover, they told the scientists there how to spend the money.

Rather than leaving these decisions up to the career science administrators and their advisers from medical schools, Congress specified sizable increases in spending for cancer of the breast, prostate, ovaries and cervix.

A year earlier, they set aside specific amounts for Alzheimer's disease research. And throughout the 1980s, they did the same for AIDS.

The ease with which advocates of individual diseases can manipulate research goals worries some. They caution that for every disease that gets an outsized share of attention, some other illness without a lobbying force will get less than it deserves.

Until AIDS, Congress had been reluctant in recent years to earmark precise amounts of money for specific diseases. Instead, those decisions were left up to the administrators at the National Institutes of Health in suburban Bethesda, Md., and their outside committees of doctors who reviewed requests for research money.

But scientists, lobbyists and others both in and out of government agree on one thing: AIDS changed everything.

Since 1982, when the federal government spent $5 million on it, the war on AIDS has grown to consume $2 billion in federal research, prevention and treatment programs. That is the same as the government spends on cancer, a disease that will kill 22 times more people this year.

Precisely comparing federal spending for various diseases is difficult. The U.S. Public Health Service provides the totals but concedes that it uses different accounting methods for AIDS. AIDS advocates contend that the government underestimates what it spends to treat cancer, heart problems and diseases other than AIDS.

But Eugene Schonfeld, a kidney cancer survivor who founded the National Kidney Cancer Assn., asserts that "The AIDS movement has radically altered health care funding by the federal government."

While AIDS activists certainly had plenty of help from scientists and sympathetic congressmen, their single-minded efforts are widely credited with keeping up the pressure that led to the vast increases in AIDS spending during the 1980s. Some quietly lobbied in traditional ways. Some became expert observers of technical developments who learned to prod the scientific Establishment to work more quickly. Still others blocked traffic, invaded the New York Stock Exchange, crashed opening night at the San Francisco Opera and disrupted a service at St. Patrick's Cathedral in New York.

No group has learned these lessons so well as the breast cancer lobby. During the past two years, many of the country's 200 local breast cancer support groups have shifted their attention from mutual reassurance to politics.

Even though breast cancer is the most heavily financed of all cancer research efforts, real progress is hard to see. The death rate is virtually the same as it was 20 years ago. In part because of better detection, the disease is now diagnosed in one in nine women at some time during their lives.

"Women will not stand for this anymore. We will not be passive. Our anger is palpable," said Amy Langer, executive director of the National Alliance of Breast Cancer Organizations.

So far, though, that anger has not resulted in the confrontational tactics used by some parts of the AIDS movement.

"Do you work within the system or do you demonstrate noisily?" asked Sharon Green of Y-ME, a national breast cancer organization. "My inclination is to first try the system. But if that doesn't work, we will see much more activism."

The system, so far, seems to be working well. Last year, the breast cancer activists enlisted the outspoken support of congresswomen, testified on Capitol Hill, held rallies around the country and organized a campaign that flooded Congress and the White House with 600,000 letters.

As a result of this and other lobbying, Congress jumped breast cancer spending by $41 million--to $133 million, a 45% increase.

This year, women in this movement say they will try for a $300-million increase in breast cancer spending. And they vow to do what they must to get it.

"We don't want to cross the line and become a fringe element or obnoxious to no end, but we are willing to become obnoxious to an end if it comes to that," said Ellen Crowley of the Women's Community Cancer Project in Cambridge, Mass.

Some, like Swanson, are willing to push the boundaries to get--and keep--Congress' attention.

Last year, they sent out "before" and "after" posters of a breast cancer victim. On one side was a pretty 35-year-old woman. On the other was same person after treatment--bald, bloated, naked from the waist up with a missing breast.

Now, she said, women who have had mastectomies are talking about demonstrating at the White House. Their tentative plan: March with their shirts off to show their scars.

"We are staying in their faces," said Swanson. "We want them to be aware that we will not go away."